DE2214265A1 - A sieve cleaner for sieve devices (classifiers) - Google Patents

Description

DIP L.-ING. HAIS W. GROEJVING DIPL.-CHEM. DR. ALFRED SCHÖN

PATENT LAWYERS Κ / Τ 10-2

Oy Tampella From Tampere, Finland

A sieve cleaner for sieve devices (Classifying devices)

The present invention relates to a screen cleaner for screening devices (classifying devices, sorting devices), and the aim of this invention is a structurally simple and effective screen surface cleaning device (Sieve bottom cleaning device) in particular for sorting paper pulp create.

Already known is the so-called Jönsson filter, in which the coarser fibers remaining as residue on the surface of the horizontal, cylindrical sieve bottom, detached from the sieve plate by a jet of water acting on the other side and through an open channel be discharged. Various drum-shaped sieve devices are also known, in which the fibers that are get caught in the sieve and clog its openings, are removed by different types of brushing elements (clearing elements) which can be moved with respect to the screen surface; this prank

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elements cause pressure fluctuations, which detach the fibers from the screen surface. With the latter Devices must run the residue before Abfühiing from the sieve over the entire sieve surface, which of course the capacity of the sieve device is reduced, since one and the same particle may find its way into the Trapped sieve bottom openings before it finally leaves the sieve. In connection with the movement of the sieve residue towards the discharge opening its concentration increases in one Measure that the usable (acceptable) fibers contained therein are no longer able to pass through the sieve, but rather pour in together with the residue.

Finnish Patent No. 43,671 is a screening device which includes a screen cleaner with spray pipes (spray nozzles) on the outside and inside of the rotating screen surface are attached, which "squirt loose" the fibers caught in the sieve and via one arranged in the interior of the sieve Lead the channel to a discharge opening at a certain distance from the spray pipes. Besides their complicated This construction also has the disadvantage that the discharge chute takes up a considerable part of the screen surface and thereby reducing the capacity of the screen.

Also known is a pressure screen device (pressure sorter, pressure classifier) which has a screen cylinder and one around it has rotating blades around which the to be sorted The screen surface facing the fibrous material near the screen cylinder is coated. This rotating wing has one over its entire length reaching cavity, which is opened via a gap to the screen cylinder and at one end communicates with the discharge opening for the sieve residue.

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The defects with which the aforementioned devices are afflicted, are, could with the present invention simple device can be eliminated. The main features of the invention emerge from claim 1.

The screen cleaner according to the invention offers compared to the previously known screening devices have the following advantages:

The coarse fibers remaining in the sieve as residue become conveyed in their entirety over the entire width of the sieve into the drain pipe of the sieve cleaner, so that the entire sieve surface is cleaned and ready to receive new material to be sieved. In contrast to already known devices, a "pulsating" wing is not used here, which is often a violent handling of the fabric causes and also fabric contamination forcing through the sieve bottom.

When working with a stationary screen cleaner, that one too is assigned stationary residue discharge pipe, results in a simple, advantageous construction, in which above all the flow of the residue is easy to control thanks to the uncomplicated construction. When working with a stationary screen cleaner there is the possibility of the detachment process and the mobility of the poorly flowing residue through technical easy installation of a spray tube inside the sieve to promote.

This also arises when working with a rotating sieve drum and stationary sieve cleaner, which is immovable compared to the accept pipe (receiving pipe), has the advantage that in the accept pipe only slight pressure fluctuations (pressure fluctuations) occur - significantly less than when working with rotating

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the sieve cleaners, which can be moved in relation to the acceptance pipe, which always cause pressure fluctuations in the accept pipeline, depending on their speed. These pressure oscillations have a particularly disadvantageous effect when in the papermaking process in front of the headbox Classifiers (sorting devices) are switched on, since the pressure vibrations caused by them in the paper cause undesirable fluctuations in the surface area.

The operation of the screening device can be seen in detail from the accompanying drawings, in which an embodiment of the invention is combined with a pressure drum screen (Pressure drum sorter, classifier) for wood pulp is shown.

Fig ^.; ] shows the sieve device in vertical section. FIG. 2 shows the device in horizontal section. FIG. 3 shows the individual components of the cleaning device

In a closed space (container) a cylindrical one rotates in the direction indicated by the arrow (Fig. 2) Sieve drum 1, onto which material is cespeisted from outside via opening 2. The sieve passage, i.e. the useful pulp, passes the sieve drum 1 and is discharged at the top via the opening 3. The coarse material to be deposited gets caught in the sieve and goes, following the drum, into the sieve cleaner 4, in which the pressure is lower than that on the outer surface (wall) of the sieve. The screen cleaner is of a laterally open part, the so-called discharge pipe 5, corresponding in its length to the drum height, formed, which absorbs the sieve residue over the entire width of the sieve. To encourage the absorption of the residue, that is

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Drainage pipe with a wing-shaped cleaning element (Space element) 6 coupled, the pulse-like pressure fluctuations and thereby loosen the residue from the sieve surface and the sieve openings. The one so released Residue gets along the inner wall of the wing to the discharge pipe 5. This cleaning element is supported in keeping it clean of the sieve surface by a mounted inside the drum Spray tube 8, the water of which dilutes the residue at its discharge point and thereby its content of usable Reduced fiber. The peripheral speed of the screen drum must be large enough to avoid tangles to prevent turbulence phenomena on the drum wall. If there should be matting, wings can be arranged near the screen drum, which cause pressure surges directed away from the screen.

The blocking element 7 is intended to ensure that the fibrous material runs in the direction of rotation of the sieve drum 1.

There is no doubt that the invention is not only limited to the form described above; the cleaning element 6 can, for example, also by means of a brush or the like. replace or in certain cases even be omitted entirely. The same applies to the locking element. Also the The number of screen cleaners is by no means limited, and e.g. with drum screens with a large diameter several such screen cleaners may be required.

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Claims (7)

22U265 claims 1. A screening device consisting of a chamber with an opening for feeding in the material to be screened (classifying) material, a cylindrical sieve bottom rotatable around its axis in this chamber and at least one stationary sieve cleaner, which has a residue discharge pipe that is open towards the sieve bottom comprises, in which there is a lower pressure than on the screen surface, characterized in that, that a cleaning element lifting the residue is coupled to the discharge pipe, and on the open one Part of the discharge pipe (5) opposite side a locking element (7) is arranged. 2. A screening device according to claim 1, characterized in that the cleaning element of a clearing strip or a wing (6) is formed, which causes a pressure drop on the sieve bottom (1). 3. A device according to claim 1 or 2, characterized in that the sieve of a Cylindrical rotating vertically about its axis or slightly conical sieve bottom (1) is formed. 4. A screening device according to one of the preceding Patent claims, characterized in that there is a spray tube (8) inside the screen cleaner is located. 209844/0726 5. A device according to claim 1, 2, 3 or 4, characterized in that the screen cleaner (4) is designed so that it removes the residue on the entire width of the sieve bottom (1) removed. 6. A device according to claim 1, characterized in that the position of the Sieve cleaner (4) relative to the sieve can be adjusted as required. 7. A device according to claim 1, 2, 3, 4 or 5, characterized in that the material to be screened (classified) is tangential from the outside the cylindrical sieve is applied and the classified material from the central part of the cylinder is discharged. · 20 9844/0726 Blank page